Water based coating for roughened metal surfaces

Abstract

Calcium or other sulfonate gel in an oil carrier (such as that of U.S. Pat. No. 4,629,753 to Quinn), optionally mixed with a small amount of sodium sulfonate and tall oil fatty acids, can be neutralized with amine, e.g. DMEA, to form a soap which can be dispersed in water. Adding an acrylic emulsion results in an acrylic coating rich in corrosion-retarding alkali metal or alkaline earth metal sulfonates. This finish on metalurgically roughened, e.g. nitrocarburized, metal forms a firm film which can resist greater than 500 hours ASTM B117 salt spray.

What is claimed is: 
     
       1. A method for protecting metallic workpieces from corrosion, comprising in combination the steps of: A. roughening the surfaces of said work pieces by sandblasting, oxynitriding, nitrocarburizing, nitrocarburizing plus oxidizing, phosphating or other metallurgical process to provide an expanded porous surface, and   B. applying to said expanded surface a waterborne corrosion protective coating composition capable of application to metallic surfaces; said composition comprising in combination: 1. colloidal metal-bearing organic/inorganic non-Newtonian complex having a total base number in the range of from about 80 to about 400 and comprising solid metal-containing colloidal particles, liquid dispersing agent and an organic molecule containing a hydrophobic portion and a polar substituent;   2. a fatty acid having an acid value in the range of about 80 to about 250, and saponification number in the range of from about 80 to about 250, and having an iodine number in the range of about 110 to 160.   3. alkali substituted organic amine.   4. film-forming organic polymer.     
     
     
       2. A method according to claim 1 wherein said composition additionally comprises: alkali metal or alkaline earth metal sulfonate having a total base number in the range of about 0.05 to about 200. 
     
     
       3. A method according to claim 1 wherein the amine comprises a triethylamine and dimethylethanol amine. 
     
     
       4. A method according to claim 1 wherein the film forming organic polymer is selected from the group consisting of alkyd resins, polyolefin resins, acrylic resins, polyester resins, and polyurethanes. 
     
     
       5. A method according to claim 1 wherein the colloidal metal-bearing organic/inorganic non-Newtonian complex comprises (1) solid metal containing particles selected from the group consisting of alkali and alkaline earth metal salts, (2) a disperse medium selected from the group consisting of inert organic liquids and low molecular weight liquid polymers, and (3) an organic compound selected from the group consisting of alkali and alkaline earth metal salts of oil soluble organic acids. 
     
     
       6. A method according to claim 1 wherein the film-forming organic polymer comprises an acrylic film-forming polymer. 
     
     
       7. A method according to claim 1 wherein said composition consists essentially of water and dispersed within said water: a. A film-forming amount of a film-forming water dispersed organic polymer in the form of disperse particles, wherein said polymer is an acrylic copolymer derived from mixtures of two or more ethylenically unsaturated monomers or at least one ethylenically unsaturated monomer and at least one vinyl double bond unsaturated monomer; and   b. a non-Newtonian colloidal disperse system comprising (1) solid metal-containing colloidal particles, (2) a liquid dispersing medium and (3) an organic compound, the molecules of which contain a hydrophobic portion and at least one polar substituent. wherein said colloidal metal-bearing organic/inorganic non-Newtonian complex is characterized by having a pH of about 7 to 10 and is present in an amount sufficient to inhibit rust formation on the substrate to which said coating composition is applied.     
     
     
       8. A method according to claim 1 wherein the organic polymer is water-reducible or water-dispersible. 
     
     
       9. A method according to claim 1 wherein the colloidal complex is a sulfonate gel.